As the weather approaches 90 degrees today in Massachusetts, I know many of you may be dreading your training run or ride.  Exercising in the heat, though, can improve your abilities and allows you to adapt to those conditions should your races occur in similar temperatures.  Now of course, you need to make sure that you’re starting out slowly in the heat, allowing yourself time to acclimate, and ensure you’re getting proper hydration and electrolytes.  But there’s another strategy that may help too – drinking a slushy!  In fact, a recent review article suggests that a pre-exercise slushy (or slushie, or otherwise known as an ice slurry) may be the most practical method for pre-exercise cooling to improve performance (1).

Several researchers have examined the effects of slushies on pre-exercise cooling and subsequent endurance performance, with great results.  Athletes who were running to exhaustion in 93 degree weather had better performance after ice slushy exhaustion compared to the control of warm fluid ingestion (2).  In another study, drinking an ice slushy before an outdoor 10K in 82 degree weather resulted in better performance time compared to drinking a beverage at ambient temperature (3).  And in another example, participants completing a treadmill run to exhaustion in 93 degree heat had better performance when they drank a flavored ice slushy beforehand compared to drinking flavored cold water.  In fact, the average time to exhaustion was 50.2 minutes after the slushy versus 40.7 minutes after the cold water (4).

Interestingly, other researchers have found that even just a mouthwash with a cold slushy ended up improving performance during a cycling time trial.  Actually ingesting the slushy had further benefits in terms of athletes reporting more “thermal comfort” and a tendency towards decreased perceived exertion (meaning the exercise felt more comfortable and easier after drinking the slushy) (5).

And some of the more recent research suggests a performance benefit during exercise as well.  Stevens et al (2013) had male athletes complete a simulated Olympic Distance triathlon, with a 0.9 mile swim, 1 hour cycling trial (at a standardized intensity), and a 10km run (self-paced), in 90 degree (F) heat.  During the cycling, the athletes either consumed a room temperature drink or consumed an ice slurry.  Those who drank the ice slurry had reduced gastric temperature, reduced perception of heat stress, and better performance time (6).

The next few days are going to be HOT, so if you’re training at all, you might consider giving this a try.  Before your workout, simply down some plain shaved/crushed ice before heading out for the run or ride.  If you have a fridge that has this the “crushed ice” function, it should be pretty easy.  If not, you could blend some ice cubes with a little water in a blender to get that slushy consistency. 

And if you’re going out for a long workout, you could also consider blending some ice cubes with some sports drink for pre-workout hydration/fueling.  Along the same lines, you could try eating a popsicle for a pre-workout snack.  This might be relevant for those of you who eat breakfast a while before your long workout and then like to enjoy a little carb intake right before the exercise, or for those of you who don’t like eating breakfast (not recommended, but I know it happens) and simply eat a gel or blocks before heading out for your long workout. On very hot days, you may feel better by whipping up a Gatorade snow cone or a Ironman Perform slushy and having that directly before exercise (rather than the gel or blocks beforehand).  Of course, you know what works best for your body, so experiment during training and find the strategy that’s right for you.  

The slushy during exercise is less practical for many of us, since it’d likely melt by the time you were ready to drink it.  However, one practical application might be to simply freeze the bottle(s) of sports drink you take with you during a long run or ride, which would help it stay as cool as possible when it’s time to drink it.  [Quick tip - you may need to open the bottle and take a sips before freezing, or allow a little space in the top of the bottle you make your drink in, to allow for expansion].

Share with us:  Will you try the slushy trick before a workout?

References:

1. Jones PR, Barton C, Morrissey D, Maffulli N, Hemmings S. (2012).  Pre-cooling for endurance exercise performance in the heat: a systematic review. BMC Med. http://www.ncbi.nlm.nih.gov/pubmed/23249542
   
2. Siegel R, Maté J, Watson G, Nosaka K, Laursen PB. (2012).  Pre-cooling with ice slurry ingestion leads to similar run times to exhaustion in the heat as cold water immersion. J Sports Sci; 30(2):155-65. http://www.ncbi.nlm.nih.gov/pubmed/22132792
   
3. Yeo ZW, Fan PW, Nio AQ, Byrne C, Lee JK. (2012).  Ice slurry on outdoor running performance in heat. Int J Sports Med. 2012 Nov;33(11):859-66. http://www.ncbi.nlm.nih.gov/pubmed/22730052
   
4. Dugas J. (2011).  Ice slurry ingestion increases running time in the heat. Clin J Sport Med; 21(6):541-2.  http://www.ncbi.nlm.nih.gov/pubmed/22064722
5. Burdon CA, Hoon MW, Johnson NA, Chapman PG, O'Connor HT. (2013).  The Effect of Ice Slushy Ingestion and Mouthwash on Thermoregulation and Endurance Performance in the Heat. Int J Sport Nutr Exerc Metab. http://www.ncbi.nlm.nih.gov/pubmed/23535809
   
6. Stevens CJ, Dascombe B, Boyko A, Sculley D, Callister R. (2013).  Ice slurry ingestion during cycling improves Olympic distance triathlon performance in the heat. J Sports Sci. http://www.ncbi.nlm.nih.gov/pubmed/23506436

Have you ever walked into a running or multisport store and looked at the abundance of products on the shelf?  Gels, shot blocks, drinks, fizz tabs, bars…it can be overwhelming!  If you’re wondering what products are best, you’re not alone – it’s a common question among many endurance athletes.

There are 6 factors to consider when selecting your fuel choice for running or cycling.  I’m going to highlight 2 of those factors in this article, and follow up with you all soon in another post highlighting the other 4 factors.  

Factor #1:  Macronutrient breakdown
Macronutrient breakdown refers to the amount of carbohydrate, protein, and fat in the product.  Quick, pop quiz – which of these is essential for us to take in during exercise?

The answer is carbohydrate!  During exercise lasting over an hour or so, you’ll need to take in carbohydrates to supply your muscles with energy.  For exercise lasting 1-3 hours, the recommended range is 30-60 grams of carbohydrate per hour.  For exercise lasting longer than 3 hours, some athletes may need up to 90 grams of carbohydrate per hour to support the prolonged activity.  

When you look at a product, check to be sure that it is a good source of carbohydrate.  Look at the label and check the number of grams of carbohydrate listed in the nutrition facts.  Be sure that you could picture yourself taking in an amount of that product that reaches our goal rates listed above. 

Many “sports bars” targeted towards strength training athletes contain high levels of protein and low levels of carbohydrate – we want to avoid these.  In fact, too much fat or protein in a product can be detrimental for endurance athletes during exercise for several reasons:
a)  It slows digestion, meaning that energy might not get to your muscles very quickly.
b)  It can cause gastrointestinal upset.
c)  You might not get enough carbohydrate to supply your muscles if you’re eating a product with excessive fat/protein.

Factor #2:  Type of carbohydrate
Your body can only absorb so much of any one type of sugar at a time.  It’s important that your fuel choices contain multiple types of carbohydrate in order to maximize absorption of those sugars, as well as reduce the chances of gastrointestinal upset.  Most engineered sports products are formulated with multiple types of sugars.  You might notice the labels say it has a “2:1 glucose: fructose ratio” or “multiple transportable carbohydrates.” 

You can also check the ingredient list to look for multiple types of sugars/carbohydrate.  Look for words like glucose, dextrose, fructose, sucrose, maltodextrin, honey, etc.  Here are a few notes that may help you navigate your way through some confusing terms:

• Dextrose and pure corn syrup are both 100% glucose (so both are the same type of sugar).
  
• Sucrose is another word for “table sugar” – comprised of 50% glucose and 50% fructose (so it has 2 different types of sugar in 1 ingredient).
  
• Honey is 30% glucose, 40% fructose, and 20% water.
  
• High fructose corn syrup is typically 45% glucose and 55% fructose (data on HFCS is controversial in terms of health - it's your personal choice whether or not to use during exercise).
  
• Agave nectars contain between 70-90% fructose and 10-30% glucose (yes, agave contains more fructose than HFCS!  Keep in mind using almost all fructose can contribute to GI upset, so I’d recommend avoiding products with agave)
  
• Maltodextrin is a polysaccharide comprised of several repeating glucose molecules (1 type of sugar).  Because maltodextrin comes in a chain of sugar molecules, it does have a lower osmolality compared to other products which can help reduce GI upset in some people.  It’s also often used in products because it’s less sweet so you avoid that ‘sickly sweet’ flavor present in some products.  Ideally, it should be combined with another type of sugar in order to promote maximal absorption and energy production.  Some companies do combine it with another source; others don’t.

Contrary to popular belief, maltodextrin is actually broken down very quickly and easily absorbed – similar to the rate of pure glucose.  It is not a “slowly released carbohydrate.”  And this is fine, because we actually don’t want a slow release during exercise – we want quickly absorbed carbs that supply our body with energy immediately.  Because the insulin response is blunted during endurance exercise, we are not worried about large insulin spikes causing a sharp drop in blood sugar levels.  Instead, we should be focused on getting quick, easily digestible carbohydrates regularly throughout exercise to provide a continuous supply of energy to the muscles.

Lastly, an important note related to ingredients - real food products are highly underutilized in sports nutrition!  Regular foods like bananas, raisins, dried cranberries, candies (sweedish fish or jelly beans), or fig newtons are all carbohydrate rich choices that naturally contain different types of sugars.  Multiple research studies prove that raisins and bananas work equally well compared to sports nutrition products in terms of performance.  In addition, regular foods are often cheaper and more readily available.

Stay tuned as I highlight the other 4 factors in an upcoming article!

Leucine is a branched chain amino acid and is one of our essential amino acids (meaning our body can’t make it, so we have to eat it in food).  During endurance exercise, the oxidation of leucine increases which has propelled researchers to investigate the impact of leucine consumption before, during, and after exercise.  So does it help endurance athletes?  Let’s find out…

The Research
There's not quite as much research out there on leucine and endurance performance as I'd have hoped, but I did find a few studies that I want to highlight.

Recovery & Subsequent Performance
In one study, researchers compared two recovery meals consumed after 2.5 hours of cycling intervals.  One of the recovery meals provided a higher amount of leucine/protein compared to the other meal (but both contained sufficient carbohydrate and were equal in calories).  After a day and a half of rest, the cyclists repeated a sprint performance test.  The researchers found that those who had the recovery meal with higher amounts of leucine/protein experienced a 2.5% increase in sprint power and a 13% decrease in perceived tiredness during the sprints (Thomson et al, 2011).  However, another study found that leucine intake post-exercise did not improve subsequent sprint performance or power –although it did reduce muscle tissue damage (Nelson et al, 2012).

Another study found that among trained canoeists, 6 weeks of leucine supplementation led to increased upper body power and work, increased total rowing time to exhaustion, and a decreased rate of perceived exertion (Crowe et al, 2006).

During Exercise
Other researchers have examined the impact on leucine intake during exercise.  For example, Pasiakos et al (2011) compared the effects of two essential amino acid drinks – one with a higher leucine concentration – on fit adults during cycling exercise.  They found that muscle synthesis protein synthesis was greater after using the leucine enhanced drink.  However, there are several issues with this study –the primary one being that no control group was used.  In addition, we know that proper recovery methods after exercise enhance muscle protein synthesis – so the research is unclear about whether it is of any use during exercise.

Recommendations:
Based on the research, it appears that leucine may be helpful with recovery and muscle protein synthesis after an endurance exercise session when used as part of the recovery meal/snack.  It is possible that it may also help with subsequent performance when used in recovery.  There doesn't appear to be enough research suggesting a performance benefit when used during exercise, though.

Also - there is no reason to spend money on pricey supplements, as selecting the correct food choices can provide all the leucine (and other amino acids) you need!  For example, in the canoeist study, the athletes were supplemented with 45 milligrams leucine per kilogram of body weight.  For a 68 kilogram (150 pound) athlete, that’s about 3060 milligrams – or 3 grams.  And remember, this was the total per day, not just in their recovery meals. 

If you take a look at our chart below, you’ll see it’s easy to get that much each day by making choices consistent with recommendations for an athlete’s diet!

You can easily incorporate foods with a higher leucine content into your recovery meals following standard recovery guidelines.

After long endurance exercise sessions, you should be replenishing your body with mostly carbohydrates to replace muscle glycogen synthesis as well as a moderate amount of protein.  The “ideal ratio” is about 3:1 or 4:1 carbohydrates to protein, although don’t worry about getting too tied down in this – just realize that the carbohydrate should be making up a larger portion of your recovery snack/meal than the protein.

The protein in the recovery food helps increase muscle glycogen synthesis if you are not getting enough carbohydrate, and also helps with muscle recovery and protein synthesis.  15 to 25 grams of protein after a long exercise session is appropriate and you can choose protein foods with higher amounts of leucine from the list above to maximize recovery.

If you find using protein powders helpful and convenient in your recovery meals, a whey protein powder will provide a good amount of leucine.  However, keep in mind that there may be quality control issues with many protein powders and that these powders are often more expensive compared to regular foods.

References:

• Crowe MJ, Weatherson JN, Bowden BF. (2006).  Effects of dietary leucine supplementation on exercise performance. Eur J Appl Physiol; 97(6):664-72. Retrieved from:  http://www.ncbi.nlm.nih.gov/pubmed/16265600
  
• Nelson AR, Phillips SM, Stellingwerff T, Rezzi S, Bruce SJ, Breton I, Thorimbert A, Guy PA, Clarke J, Broadbent S, Rowlands DS. (2012).  A protein-leucine supplement increases branched-chain amino acid and nitrogen turnover but not performance. Med Sci Sports Exerc; 44(1):57-68. Retrieved from:  http://www.ncbi.nlm.nih.gov/pubmed/21685813
  
• Pasiakos SM, McClung HL, McClung JP, Margolis LM, Andersen NE, Cloutier GJ, Pikosky MA, Rood JC, Fielding RA, Young AJ. (2011).  Leucine-enriched essential amino acid supplementation during moderate steady state exercise enhances postexercise muscle protein synthesis. Am J Clin Nutr; 94(3):809-18.  Retrieved from:  http://ajcn.nutrition.org/content/94/3/809.long
  
• Thomson JS, Ali A, Rowlands DS. (2011).  Leucine-protein supplemented recovery feeding enhances subsequent cycling performance in well-trained men. Appl Physiol Nutr Metab; 36(2):242-53. doi: 10.1139/h10-104.  Retrieved from:  http://www.ncbi.nlm.nih.gov/pubmed/21609286